1. Field of the Invention
The present invention relates to an electrical plug connector half in particular, to a plug connector half connectable with another matching electrical plug connector half and including a housing having a cable entrance, a traction force compensator for a cable and located in the housing in a vicinity of the cable entrance, at least one contact carrier located in the housing, a cap secured to the housing at its end in which the cable entrance is provided, a union overlapping the housing and an end of the contact carrier projecting beyond an end of the housing opposite the housing end in which the cable entrance is formed, the housing having axially spaced, radially projecting annular webs forming slide bearing regions for supporting the union for rotation about its longitudinal axis, and the union having an inner thread for connecting the plug connector half with the matching plug connector half, means for preventing an axial displacement of the union relative to the housing, and safety means for preventing an inadvertent rotation of the union in a direction corresponding to release of threaded connection of the plug connector halves.
2. Description of the Prior Act
An electrical plug connector half of a type discussed above is described in German Patent No. 4,301,504. In the known plug connector half, the union is rotatably supported on the connector half housing and is associated with locking means that prevents an inadvertent rotation of the union. The locking means consists of a locking crown and matching locking means engaging in the indentation of the crown. The locking crown is formed on an inner circumference of a plastic ring mounted in an annular groove formed at an end of the union adjacent to the cable entrance. The plastic ring is held in the groove by snap-action means. The matching locking means is formed by radially projecting noses provided on the outer circumference of the housing and constantly engaging in the indentation of the crown provided on the union. Because in this embodiment, the plastic ring and the housing are both formed of plastic materials, the holding force of the safety means can only be overcome by an increased force sufficient for compressing the engaging into each other locking elements. Such safety means, as discussed above, requires that the housing also be formed of a compressible plastic material which can be compressed with an acceptable force and have, in view of the fact that the crown is provided at the rear end of the union, a sufficient length.
According to German Patent No. 3,730,033, the housing is formed of two parts connectable by bolts and is provided with a circumferential toothing formed as saw toothing and provided on two spaced from each other longitudinal section. The first toothing is designed to prevent an inadvertent loosening of the threaded connection of the two housing parts, and the second toothing is designed to prevent an inadvertent loosening of the threaded connection of the housing with a cap provided at the cable entrance end of the housing. The inadvertent rotation is prevented as a result of the cap being pressed with its inner circumference in the circumferential toothing provided on the housing. However, such means makes damage-free removal of the cap away from the housing extremely difficult. Moreover, such safety means is unsuitable for preventing an inadvertent rotation of union rotatably supported on the housing.
Each of the two, above-described safety means for components of electrical plug connectors or their halves is based on the use of the deformation resistance of the plastic material and requires application of uniform forces for insertion of the safety means and for overcoming its holding force. This is very inconvenient for the operational personnel.
Accordingly, an object of the present invention is to provide safety means that can be simply and economically produced and can be inserted with a relatively small expenditure of force.
Another object of the present invention is to provide safety means which would provide a number of locking position of the union on the housing.
A further object of the present invention is to provide safety means that would not require increase of the dimensions of the plug connector or its halves.
These and other objects of the present invention, which will become apparent hereinafter, are achieved by arranging the safety means in an annular space between the axially spaced slide bearing regions of the housing, with the safety means including a circular saw toothing provided on one of the union and the housing and spring-biased pawls means cooperating with the saw toothing provided on another of the union and the housing.
The safety means according to the present invention is designed for use in plug connectors which are subjected during operation to constant shocks and, in particular to high vibrations. More specifically, the inventive safety means is designed for use in plug connectors halves which are to be connected with other halves mounted on apparatuses which generate shocks and vibrations, and where a spontaneous loosening of the union, which connects the two halves, as a result of shocks and vibrations, needs to be prevented.
In order to facilitate establishing of a plug connection by screwing the union on the threaded portion of the another matching plug connector half, the safety means needs to be so design that the screwing is effected with a relatively small force expenditure.
The use, in connection with safety means formed of saw toothing and pawls cooperating with the saw toothing, spring means for biasing the pawls in the engagement direction, permitted to reduce the force expenditure, necessary for the mounting of the safety means, to a very small value, much smaller than was necessary when the safety means, which was based on the compressibility of the safety means components, was used. A particularly small expenditure of force necessary for mounting of the safety means is achieved when the spring-biasing force is at least limited essentially to a force necessary to insure engagement of the pawls with the saw toothing, and the holding effect is primarily obtained by forming cooperating flanks of the saw toothing and the pawl so that they extend steeply in a direction of rotation of the union which results in loosening or release of the threaded connection.
Low insertion and high holding forces are obtained particularly easily when the pawl-biasing spring is formed as a leaf spring and, in particular, as a spring arm or a spring band. Arranging, according to the present invention, the safety means in the already available hollow space in the plug connector half insures that no increase of the dimensions of the connector half is necessary for accommodating the safety means.
According to an advantageous embodiment of the present invention, the saw toothing is provided on an inner circumference of the union, and the pawls are supported on the housing by resiliently deformable support arms.
In order to reliably prevent an inadvertent rotation of the union in the loosening direction even when the pawls are biased into engagement with the saw toothing with a light spring force, according to a further advantageous embodiment of the present invention, there are provided four pawls which are supported pairwise by respective spring bridges on the housing.
According to the present invention, each bridge is formed as an arcuate member having in its middle region a thickness approximately corresponding to a width of the annular space between the union and the housing, with the thickness gradually decreasing to the pawl-carrying bridge regions, so that resiliently deflectable bridge sections are formed. Though, the pawls can be mounted on several bridges, for economical production, the pawls are mounted pairwise on two semi-circular spring bridges.
For purposes of facilitating the assembly of the safety means, the spring bridges are supported on a sleeve and against a sleeve band provided on the sleeve. The sleeve, together with the spring bridges, forms a sub-assembly that can easily be inserted into the plug connector half. The inner diameter of the sleeve corresponds to the outer diameter of the housing in the region between the spaced annular webs. The spring bridges are mounted on a reduced diameter portion of the sleeve.
According to a particularly advantageous embodiment of the present invention, each spring bridge has a middle region and opposite end regions spaced from the middle region. The middle and end regions have a thickness corresponding to a width of a space between the sleeve and an addendum circle of the saw toothing, which is provided on the inner wall of the union, and the pawls of the respective pawl pair are arranged on respective bulging regions of the spring bridge extending between the middle region and the respective opposite end regions, with the bulging regions forming resiliently deformable arms.
The sleeve has approximately diametrically opposite stubs, and each spring bridge has, in the middle region, an opening in which a respective stub engages.
The foregoing structure provides for a particular reliable support of the pawls with respect to the housing or on the sleeve even when the bulging regions are made rather then in order to insure that only a light force acts on the pawls. This insures that upon tightening of the union, the rotation of the union in the loosening direction is prevented by a very small expenditure of force.
Generally, a high resistance of the safety means, which prevents the rotation of the union in the loosening direction is achieved by providing a saw toothing and pawls the respective flanks of which gradually ascend in the rotational direction of the union corresponding to establishing of a connection between the two plug connector halves, with the respective other flanks of the saw toothing and the pawls ascending steeply. The steep ascention of the other flanks results in a resistance to displacement of the pawls relative to the saw toothing substantially increasing upon rotation of the union in a direction corresponding to release of the connection between the plug connector halves.
The foregoing formation of teeth of the saw toothing and pawls results in a small expenditure of force necessary for securing the union on the second connector half, on one hand, and in an increased resistance to rotation of the union in the loosening direction on the other hand.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.